Although quantitative and qualitative changes in secreted glycoproteins have been implicated in the pathogenesis of a number of human respiratory diseases, there is suprisingly little knowledge available concerning the structure of these macromolecules or the role they play in even normal physiological conditions. The primary goal of ths proposal is aimed at determining the entire or partial sequence of sugar residues in the oligosaccharide portions of the complex carbohydrates (CC) associated with mucous and serous secretions and the surface glycocalyx of respiratory tract epithelial cells. At the light microscopic level, emphasis will be placed on determining the structure of oligosaccharides within stored secretions of several morphologically recognizable cell populations associated with respiratory epithelium including surface mucous cells, glandular mucous cells and serous cells. A battery of lectins having well established carbohydrate binding specificities for terminal sugars in conjuction with sugar-specific exoglycosidases will be used for the in situ sequencing of sugar residues on oligosaccharide side chains. Ultrastructural histochemical studies will concentrate on defining the intracellular distribution of CC within various secretory organelles of respiratory tract epithelial cells and characterizing the structure of oligosaccharides associated with cell surface glycoconjugates. Newly developed post-embedment ultrastructural histochemical techniques allowing a direct comparison of staining with several methods in the same cell and in some cases in the same cellular organelles will be utilized. Respiratory tract epithelium from mice, rats and humans will be examined at both the light and electron microscopic level and results will be compared. Initial studies will focus on localizing and characterizing CC in healthy members of the above species. When sufficient baseline data has been obtained, emphasis will shift to detecting possibly alteration in the structure of respiratory tract CC in response to a variety of injuries and pathological conditions.